In aortic valve replacement surgery, a cardioplegic solution or fluid is introduced into the coronary arteries to lower the temperature of the heart and make it motionless. A single cannula is used to dispense the cardioplegic solution into each coronary artery. The cannula is an elongated flexible tube having an enlarged head at its distal end. An example of a cannula for dispensing cardioplegic solution into the heart as shown by Carpenter et al in U.S. Pat. No. 4,416,280. A cannula of a selected size is slipped into the coronary lumen until the entire head engages the wall of the coronary artery. Forcing the cannula into passage of the coronary artery can traumatize the artery tissue and cause scarring. The left coronary artery in some patients bifurcates a few millimeters from the wall of the aorta. This makes the cannula insertion difficult as there is insufficient length of the coronary artery to accommodate the entire head of the cannula.
The right coronary artery in some patients makes a right angle turn in close proximity from its origin from the aorta. The insertion of a cannula to the right coronary artery can injure the artery at the point of the angulation or bend in the artery. The cannula must be gently inserted to safely make a right angle turn. The use of the cannula to achieve cardioplegia utilizes valuable surgeon's time during the operating procedure. The cannula can cause trauma to the coronary ostia and to the proximal portion of the coronary artery.
In certain operative procedures in infants and children with associated aortic insufficiency, it is not possible to utilize cardioplegic solution, because coronary perfusion cannulas of sufficient small size are not available. Other means are required to lower the temperature of the heart.